12th International Conference on Harmful Algae

INTERNATIONAL SOCIETY FOR THE STUDY OF HARMFUL ALGAE12 th <strong>International</strong> <strong>Conference</strong> on Harmful Algae, Copenhagen, Denmark, 4-8 September 2006D9 in comparison with that reportedfor strain T3. Intra- and extracellulartoxins were determined bypost-column derivatization LC withfluorescence detection; structureswere confirmed by LC-MS/MS. Incontrast to strain T3, which isgrowth sensitive to NaCl (10mM),strain D9 grew at NaClconcentrations as high as 17 mM.At this high salt concentration,intracellular toxins levels in strainD9 cells were reduced by 80% and95% for GTX2/3 and STX,respectively, by 36 h, concomitantwith extracellular increase inGTX2/3. Decline in intracellular STXlevel was transient and returned tonormal by 156 h. Extracellular toxinrelease was not associated with celllysis because cell integritydetermined by chlorophyll a contentand cell morphology wasmaintained. These data suggestthat D9 exhibits an active toxinrelease in response to high salinity.Regulation of PSP toxin synthesisand release appears to bedifferentially regulated by strains T3and D9 under salt stress.Fondecyt 1050433; Núcleo MilenioEMBA:PO4/007-F.PO.11-13Diatom effect on dinoflagellategrowthSession: PO.11 - AllelopathyK SpillingFinnish Environment Institute, HELSINKI,FinlandDiatoms release secondarymetabolites, but little is known aboutthe ecological effect of theseexudates. This study wasconducted to test if diatom exudateshave any effect on co-occurringdinoflagellates. For this purposegrowth and primary production of:Peridiniella catenata, Scrippsiellahangoei and Woloszynskiahalophila were determined infiltrates (0.2µm and 2.0µm) ofdiatom cultures and aged,autoclavated seawater. The growthof P. catenata and W. halophila wassignificantly reduced in filtrates ofdiatom cultures compared with agedseawater; S. hangoei, on the otherhand, had increased growth rate indiatom filtrates. The response wasgenerally greater in the 2.0µmfiltrate compared with the 0.2µmfiltrate. The instantaneous primaryproduction was, however, notaffected by the origin of the growthmedia. The results indicate thatdiatom exudates do affect thegrowth of the studieddinoflagellates. This effect is notdue to immediate change in shortterm primary productivity but ratheraffects other growth regulatingmechanisms.PO.01-02Dinoflagellate cysts from NewZealand ports and harbours, withemphasis on the distribution ofharmful and potential invasivespeciesSession: PO.01 - GeneticsR Stewart, FH ChangNational Inst. of Water & Atmosph. Res.,WELLINGTON, New ZealandOver the period 2003-2005, 179sediment samples, collected fromfourteen New Zealand ports andharbours, were analysed. Thesamples were part of a large-scalebaseline survey for the NZ Ministryof Agriculture & Forestry,Biosecurity New Zealand. Morethan twenty distinct cyst types,representing nine dinoflagellategenera, were identified. Thenumber of cyst types from individual284